Control for automatic slack adjusters



Aug. l2, 1952 A, w. DoNoP CONTROL FOR AUTOMATIC sLAcx ADJUSTERS 3 Sheets-Sheet 2 Filed Nov. 8. 1949 INVENTOR.

Aug. 12, 1952 A, W, DONOP 2,606,634

CONTROL FOR AUTOMATIC SLACK ADJUSTERS Filed Nov. 8, 1949 3 Sheets-Sheet 5 IN VEN TOR.

Patented Aug. 12, 1952 CONTROL FOR AUTOMATIC SLACK ADJUSTERS August W. Donop, Chicago, Ill., assignor to Ajax- Consolidated Company, Chicago, Ill., a corpo,-

ration of Illinois Application November 8, 1949, Serial No. 126,174

1 Claim. v l

This invention relates, generally, to railway car brake rigging, and it has particular relation to mechanism for controlling automatic slack adjusters therefor. This invention is disclosed in conjunction with the automatic slack adjuster of copending application Serial No. 122,941, led October 22, 1949, and assigned to the assignee of this application.

The automatic slack adjuster, above referred to, operates in conjunction with the air brake piston to take up a small amount of slack in the brake rigging when the piston travel exceeds a predetermined amount. If the slack, as originally present in the brake rigging after assembly on a car or after renewal of the brake shoes, is not within certain limits, it is likely that several applications of the brakes will be necessary before there is any braking effect on the car. One reason for this is that the automatic slack' adjuster takes up only a small amount of slack each time that the brakes are applied and there is a travel of the air brake piston beyond a predetermined position. Under these conditions, the travel of the piston in the air brake cylinder will exceed predetermined minimums that have been established and may require that the car be cut out of a train until the slack is properly adjusted.

There is also the possibility that too much slack may be taken out of the brake rigging during the original installation or after the brake shoes have been renewed. This will result in a travel, of the piston in the air brake cylinder which is too little-to permit proper application of `the brakes. The brakes will be applied too soon and with too great force so that the wheels of the car with the brake rigging having too little slack will tend to slide whenthe brakes are applied. Also there is a possibility that a part of the brake rigging may be broken because of the excessive forces which are involved.

Accordingly, among the objects of this invention are: To provide a predetermined amount of slack in a brake rigging of a railway car so that the slack present is always within predetermined limits, being not too great so as to prevent application of the brakes or too little with consequent excessive braking pressure; t/o `provide for controlling an automatic slack adjuster` for a railway car brake rigging so that there will always provide a lost motion connection ,nthe'aute 2 matic slack adjuster to perform this function; and to adjust the slack by winding an inextensible member, such as a chain connected at its free end to the fulcrum point of a floating fulcrum lever, on a drum either manually or automatically through a ratchet wheel operated in response to predetermined'travel of the air brake piston, there being a lost motion connection between the drum and the ratchet wheel.

Other objects of this invention will, in part, be obvious and in part appear hereinafter.

This invention is disclosed in the embodiment thereof shown in the accompanying drawings and it comprises the features of construction, combination of elements and arrangement oi parts which will be exemplified in the construction hereinafter set forth and the scope ofthe application of which will be indicated in the appended claim.

For a more complete understanding of the nature and scope of this invention, reference may be Yhad to the following detailed description, taken together with the accompanying draw# ings, in which: S

Figure 1 illustrates, schematically and' diagrammatically, a brake rigging systemV that vis used customarily on railway cars and having applied thereto the present invention;

Figure 2 is a top plan View of the automatic slack adjuster constructed in accordance with this invention;

`Figure 3 is a View looking from the left end of the slack adjuster as shown in Figure 2;

Figure 4 is a detail sectionalview, taken generally along the line 4-4 of Figure 3, and showing certain details of construction;

Figure 5 is a view, similar to Figure 4, but showing the manner in which the drum on which the -chain is wound is prevented from rotating in a reverse direction in the event that the holding pawl should fail to hold and thus prevent its reverse rotation as it is intended normally to do;

Figure 6' is a view, in end` elevation, of the chain winding drum and cooperating ratchet wheel which are interconnected by a lost motion connection;v ,l

Figure 7 lis a view, in side elevation, of'the chain windingdrurn and ratchet wheel shown Ain vFigure v6 A and I Figure 8 is a longitudinal sectional -view through the chain Winding drumrand ratchet Vwheel showing them mounted on a shaft#v VReferring now particularly to Figure lioffthe drawings, it will be observed that the "reference character IIJy designates, generally, a conventional brake rigging which is used widely on railway cars. The brake rigging I9 includes brake beams II, I2, I3, and I4 which carry brake shoes at their ends that are hung by links from the truck side frames. This construction is well known to`thcse skilled in the'art, and, accordingly, itis-not further shown nor described herein. The brake beams II and I4 are pivoted on truck dead levers I5 and I5 that are pivoted to dead lever fulcrums or links I1 and I8. rlhe fulcrums or links I1 and I8 are pivoted to `arms I9 and 20 that are carried by the truck side frames. It will be observed that the truck dead levers I5 and I6 are pivoted at 2| and 22 to thefulcrums or links I1 and I3 and that these pivot points are adjustable therealong. The lpurpose of these adjustments is to provide for taking up slack manually in the brake rigging I v'as the brake shoes wear.

The brake beams I2fand I3 `arecarriedby-.and pivoted on truck live levers 24 and 25 which .are connected by bottom rods 26-and 21 to the truck dead levers I and I6, respectively. The truck live levers 24 and 25 are connected to top truck rods 3U and 3I through which the braking power is applied for moving the brake beams II, -I2, I3, and I4 and the brake shoes carried lthereby toward the wheels'for applying the brakes. The top truck rod 39 is pinned toa cylinder lever Y32 while the top truck rody 3l -is pinned to a floating fulcrum lever- 33 Whose fulcrum is indicated ait-34 and-the position of which may be adjusted by an 4'automatic slack adjuster, shown Vgenerally at 35, `inwhich the present .invention is embodied. The'oatingfulcrum.lever :33 Vis connected intermediate itszends bya cylinder rod :36 to the cylinder-.lever 32. The latter has a, .push rod 31-pivoted thereto. It will be noted that-the push-rod 31::has apiston 38 atthe opposite yend which is slidable'in'an air brake cylinder 39. Within the air'brake cylinder -39 there. is a coil compression spring 40 which actsto release the brakes when the air pressure is released from theairfbrake cylinder 39. Air pressure for movingithe piston 38 toa'pply the brakes is supplied througha conduit-1I -from'a car -air reservoir42. The flow of air from the reservoir `42 :to the Acylinder 439 is controlledfby' a valve43` in conventional manner.

The brakes also may be applied through a hand brake rod 44 byva hand brake mechanism that is indicated, generally,aat^45. It willbe noted that the hand brakev rod-44 alsois connected to the cylinder lever 32.

As indicated hereinbefore the present invention is directed particularly t0 thezautomatic slack adjuster 35 whichis shown in moredetail in Figures 2, 3 `and 4 of the drawings. .As'there shown, theautomatic slack adjuster 35 includes a support`48 which is arranged to rbe bolted or otherwise secured to'the car body. vThe support 48 carries a frame, indicated generally at 49, having a slot 50,*Figure 4,.therein into which thezfulcrum end of thefloating fu1crum-leverr33 projects.

The fulcrum end of the floating fulcrumllever 33 is secured by a' pinl 5I to a clevis 52v that is attached to one :end `of a flexible inextensible member such as a chain 53. The other end of -the'chain 53 is connected by a pin 54 to adrum 55 and is arranged to ybe wound thereonfsovas to shift the position of the fulcrum point 34 of the floating fulcrum lever-'33 and take up the slack inthe brake rigging I0.

The drum is mounted for rotation with a shaft 55 which extends through side frame members 51 that form a part of the frame 49. The shaft 56 is rotatably mounted and provision is made for making the drum 55 fast thereon. For this purpose a set screw 58, Figure 8 may be employed.

Loosely mounted on the shaft 56 is a ratchet wheel 59. The ratchet wheel 59 is connected to the drum 55 by means of a 10st motion connection that is indicated, generally, at 69. The lost m0- tion connection 69 is made up, in accordance with this invention, of an arcuate slot 6I in the ratchet Wheel '59 and a detent 62 projecting from the drum .55*axially into the arcuate slot 6 I. Driving engagement between the drum 55 and ratchet wheel r59 is .hadwhen the detent 62 is at one end 63 or the other 64 of the arcuate slot 6I. The manner in which advantage as taken of the lost motion connection 60 between the drum 55 and the ratchet wheel 59 will be .described lin detail hereinafter.

In order to prevent reverse rotation of the ratchet wheel 59 and to prevent reverse rotation of the chain winding drum 55 when the brakes are applied, the detent 62 being at the end 63 of the arcuate slot 6 I, a holding pawl 65 is employed. The holding pawl 65 is rockably mounted on a shaft 66 which extends between the frame side members 51. The opposite end 61 of the pawl 65 acts as a counterweight to bias thepawl 65 into operative engagement with the teeth of the ratchet wheel 59. This end 61 can be grasped so as to swing the pawl 65 out of operative engagement with the lratchet Wheel 59 when it'is desired to unwind the chain 53 from the drum 55 as may be desired when thebrake shoes are being replaced or the brakerigging is being readjusted for some-reason.

Slack in the brake rigging ID can be taken .up manually by rotating the drum 55. For this purpose theshaft 56 has openings 68 in its ends 69 for receiving ra bar or suitable tool (not shown). Alternatively, the end.69 of the shaft 56 can have at sidesto accommodate va wrench. It will be understood that the ends 69 of the shaft 56 con-'- stitute manually operable means, referred to in the claims, for rotating the drum 55 so as to wind the chain 53 thereon and shift the position of the fulcrum point 34 of the noating fulcrum lever 33 and, thereby, take up the slack in the brake rigging III. l

Inorder to take up the slack in the brake rigging I0 automatically when the travel of the piston 38 :in the air brake cylinder 39 exceeds apredetermined amount, provision is made for rotating the ratchet wheel 59 forwardly a limited amount in order t0 accomplish this purpose. AIn order-to .do this an operating pawl 13 is arranged to cooperate with the ratchet wheel 59. As shown in Figure 4 the operating paw1 13 is pivoted at 14 on one arm 15 of a yoke that is indicated, gen- -erally, yat 16. The yoke 16 is lrockably mounted on ashaft 11 which extends between and is carried by the frame side members 51.

In order to rotate the ratchet wheel 59 forwardly by corresponding forward movementv of the operating pawl 13, a coil compression spring 18 is employed. It will be noted in Figure-4 that one end of the spring 18 `bears against a portion of the support 48 while its other end is arranged to act through a rod 19 having a ball shaped head l8i) at its opposite end which interiits with a socket 8l in the arm 15. It will be understood that the spring 18 is compressed by means to be described and that, when the force applied to compress it is removed, it expands and moves the operating pawl 13 forwardly or to the right to effect a corresponding movement of the ratchet wheel 59.

` The yoke 16 also includes an arm 84 which is movable conjointly with the arm 15. The arm 84 is pivoted at 85 to a clevis 86 which may be threaded on one end of a push rod 81.

As shown more clearly in Figure 2 of the drawings, the other end of the push rod 81 is arranged to be operated by a diaphragm type piston as indicated, generally, at 88. The diaphragm type piston 88 includes a head 89 which is connected directly to the left hand end of the push rod 81. A ilexible diaphragm 98 interconnects the head 89 with a wall 9| of a slack adjusting air cylinder that is indicated, generally, at 92. A coil compression spring 93 is provided inside of the slack adjusting air cylinder 92 for returning the head 89 to the initial position shown in Figure 2. The spring 93 acts in the same direction as the coil compression spring 18 and, if desired, may be omitted.

Air for operating the diaphragm type piston 88 is supplied through a conduit 94 which is connected at 95, Figure 1, to the air brake cylinder 39. It will be observed that the conduit 94 is connected to the air brake cylinder 39 at such a position, for example, at a position where the piston 38 must move through a distance of seven inches, that the slack in the brake rigging Il) is taken up automatically only after the amount thereof exceeds a predetermined value. Thus, as long as the slack in the brake rigging III is not suilicient to permit lthe piston 38 to travel in applying the brakes sulciently far to uncover the opening into the conduit 94, no air pressure is applied to the diaphragm type piston 88 and no automatic adjustment of the slack in the brake rigging II) is made.

There is a remote possibility that the holding pawl 85 may not perform its intended function of preventing reverse rotation of the ratchet wheel 59 and drum 55. Such action might occur in the event that the ratchet Wheel 59 were coated with ice and the drum 55 were advanced one notch in taking up the slack automatically in the brake rigging I8. In such case the ice in the next slot might prevent the holding pawl 85 from engaging with the next tooth on the ratchet l wheel 59. It is important that the fulcrum point 34 of the iioating fulcrum lever 33 be held stationary when the brakes are applied for otherwise, it is not possible to apply them. If the drum 55 should not be prevented from rotating in a reverse direction by the holding pawl 65, when the valve 43 is opened in attempt to apply the brakes, the drum 55 will be rotated in a reverse direction and will carry with it the operating pawl 13 and parts attached thereto. Since these parts are relatively light and weak, they cannot resist the reverse rotation of the drum 55 and, as a result, the brakes will not be applied since the fulcrum point 34 is not held stationary. Further, the automatic slack adjuster 35 may be severely damaged or possibly substantially destroyed.

With a view to preventing the reverse rotation of the drum 55 and the ratchet wheel 59 under such conditions where the holding pawl 65 does not perform its intended function, the operating pawl 'I3 is provided with an inclined end surface 98 that is arranged to engage a transverse stop pin 99 which extends between and is carried by the frame side members 51. Now, if

the holding pawl 65 fails to prevent reverse rotation of the drum 55 and the ratchet wheel 59, the operating pawl 13, which is biased by its weight into engagement with the ratchet wheel 59, moves rearwardly as the drum 55 and ratchet wheel 59 are rotated in a reverse direction. However, such movement is limited by the engagement of the end surface 98 with the transverse stop pin 99. Not only does the pin 99 prevent further reverse rotation of the drum 55 and ratchet wheel 59 but also, because of the inclined end surface 98, the operating pawl 13 is moved into wedging engagement with the ratchet wheel 59, as indicated more clearly in Figure 5 of the drawings. Here the possible position of the holding pawl 65 is indicated which would permit the drum 55 and ratchet wheel 59 to rotate in a reverse direction in the event that the transverse stop pin 99 were not provided.

In describing the operation of the present invention it will be assumed that the `slack in the brake rigging I8 initially is adjusted by locating the fulcrum points 2I and 22 along the dead lever fulcrums I1 and I8. As will appear hereinafter, additional adjustment of the slack in the brake rigging I0 can be made by the insertion of a bar in the opening 68 in one of the ends 69 of the shaft 56. Preferably the adjustment of the fulcrum points 2| and 22 is such that no part of the chain is wound on the drum 55. Also it will be assumed that the detent 62 of the lost motion connection 68 engages the end 63 of the arcuate slot 6I. Under these assumed conditions it will further be assumed that the proper amount of slack is left in the brake rigging I0 for normal operation. As long as the piston 38 in the air brake cylinder 39 is not required to travel past the point where the conduit 94 is connected to the air brake cylinder 39, no operation of the automatic slack adjuster takes place. However, when the slack in the brake rigging I0 is such that the piston 38 is required to move in the air brake cylinder 39 so as to uncover the conduit 94, on the next application of air to the air brake cylinder 39, air will be supplied through the conduit 94 to the slack adjusting air cylinder 92. The diaphragm type piston 88 will be moved to the right as viewed in Figure 2 and, through the push rod 81, the yoke 16 will be rocked a corresponding amount. The operating pawl 13 will be moved rearwardly tol engage the next tooth of the ratchet wheel 59 and the coil compression spring 18 will be compressed correspondingly. During this interval the drum 55 is prevented from rotating in a reverse direction by the holding pawl 65 in engagement with the ratchet wheel 59 and the detent 82 bearing against the end 63 of the slot 6I. l

No further action takes place until the air pressure is released and the brake rigging I 0 no longer applies the brakes. The release of air pressure from the slack adjusting air cylinder 92 permits the spring 18 and the spring 93 to move the operating pawl 13 forwardly and to effect a corresponding forward rotation of the drum 65. This is permitted since the brakes are not applied and the fulcrum point 34 of the floating fulcrum lever 33 is not held Stationary. The chain 53 1s Wound on the drum 55 a slight amount; The forward rotation of the drum 55 is permitted by .the holding pawl B5 which, since it is biased by the counterweight action of the opposite end 61 acts to engage the next tooth of the ratchet wheel 59 and prevents reverse rotation of the drum 55. In4 th1s manner the slack in the brake rigging I0 7 is vv,autom atically adjusted in small increments andismaintained at'a predetermined value as will be understood (readily.

There is the distinct vpossibility that the slack in the brake rigging I!) may not l,be taken out of it initially or when the brake shoes are renewed or adjustments made on the brake rigging t so as to obtain initially proper operation of the brakes. If suiiicient slack is not taken out of the brake rigging I0 initially, then the piston 38 in the air brake cylinder 39 will move to the end of its stroke and air will be applied to the slack adjusting air cylinder 92. The drum 55 will be rotated forwardly through a small increment ,and acorresponding amount of the slack will be taken out of the brake rigging IU. The amount of slack taken out. of the brake rigging I9 under these conditions purposely is small. However, under these particular assumed conditions, suflicient slack is not taken out of the brake rigging l0 so as to permit proper application of the brakes. `Therefore, if `a car with the brake rigging so adjusted is coupled onto a train and the brakes are applied, the brakes on this particular car will not be applied. Obviously it will require several applications of the brakes before the automatic slack adjuster 35 is able to take up suicient slack in the brake rigging lil so as to permit proper application of the brakes.

Itis to avoid this difliculty that provision is made for rotating the chain winding drum 55 manually. Thus, after the truck dead levers l and I6 are positioned on the dead lever fulcrums l1 and ,l 8, respectively, a bar or other suitable tool is inserted in one of the openings 68 in one of the ends of the shaft 55. The chain winding drum 55 then is rotated forwardly to take up the remaining slack in the brake rigging ii).

Now Yit is essential that too much slack not be taken out of the brake rigging I9 for otherwise, sulicient travel of the piston 3S in the air brake cylinder 33 will not be permitted. This might result in the application of excessive stress to the brake rigging I0 and possible breakage of a portion of it s uch as one of the pins interconnecting the levers or the levers themselves. In order to avoid taking `up too much slack in the brake rigging I0 the lost motion connection 60 isprovided. When the chain winding drum 55 is rotated forwardly by the manually operable means, the ratchet wheel 59 remains stationary until thedetent 62 engages the opposite end 64 of the arcuatev slottl. Thus, no matter how much effort is applied in rotating the chain winding drum 55 forwardly, there willl always be a predetermined amount of slack left in the brake rigging YI0 which corresponds to the length of the arcuate slot 63. On the next application of the brakes, the detent 62 willtravel to the end 63 of the arcuate slot Si before rany braking effort is applied. The length of the arcuate slot 6| is determined by the amount of slack which should be left in the brake rigging I0 to permit proper movement of the piston 38.

Since certain changes can be made in the foregoing. construction and different embodiments of titel-invention` can be made without departing from the spirit and scope` thereof, it is intended that all matter shown in the accompanying drawings and' described hereinbefore shall be interpreted as illustrative and notrin a limiting sense.v 'l

What is claimed as newis: l

Means for adjusting automatically the slack in railway car Vbrake rigging and controlling the 8 same byadjusting the fulcrum point of the-floating v fulcrumleve'ror the like thereof operated by a piston in an air brake cylinder comprising, in combination, a rotatably mounted shaft, manually operable means for rotating said shaft, a drum fast on said shaft, a chain for connection at one end tothe fulcrum point of said fulcrum Ylever and connected at its other end to said drum for winding thereon on forward rotation thereof to ytake up the slack in said brake rigging, a ratchet wheel loose on said shaft juxtaposed to one'end of said drum and having an arcuate slot therein, a detent extending from said one end of said ratchet wheel into said slot whereby limited relative movement between said drum and ratchet wheel is permitted, a holding pawl biased into engagement with said ratchet wheel and acting to prevent reverse rotation thereof, a rockably mounted yoke, an operating pawl having an inclined end surface pivoted t0 one arm of said yoke and biased into engagement with said ratchet wheel, a. transverse pin in the path of said end surface of said operating pawl and adapted to be engaged thereby on failure of said holding pawl to prevent reverse rotation of said ratchet wheel for wedging said operating pawl into engagement therewith and preventing further reverse rotation thereof, a coil compression spring connected to said arm and acting to move said operating pawl so as to rotate said ratchet wheel and drum forwardly, a slack adjusting air cylinder having a piston therein connected to the other arm of said yoke, and a conduit from said slack adjusting air cylinder for connection to said air brak-e cylinder at a location where operating pressure is applied to said slack adjusting air cylinder after the piston in said air brake cylinder has moved to a predetermined position in applying the brakes whereupon said piston in said slack adjusting air cylinder rocks said yoke, compresses said spring and moves said operating pawl rearwardly to engage the next tooth of said ratchet wheel, the release of air pressure from said air brake cylinder and from said slack adjusting air cylinder permitting said coil compression spring to rotate said ratchet wheel and drum forwardly, the aforesaid limited relative movement between said drum and said ratchet wheel provided by said detent and said arcuate slot permitting said drum to be rotated forwardly by said manually operable means to take up the slack in said brake rigging without causing corresponding forward rotation of said ratchet wheel until said detent reaches one end of said arcuate slot, reverse rotation of said drum being permitted on application of air to said air brake cylinder and consequent movement of said brake rigging until said detent engages the opposite end of said arcuate slot whereby a predetermined amount cf slack is left in said lbrake rigging after the slack therein is taken up by said manually operable means.

AUGUST W. DONO-P.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,407,628 Berry et al Feb. 2l, 1922 1,964,333 Sauvage June 26, 1934 2,097,533 Redford Nov. 2, 1937 2,433,139 Martin Dec. 23, 1947 

